The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Muriel Barberi-heyob - One of the best experts on this subject based on the ideXlab platform.
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Realtime tracking of the photobleaching trajectory during photodynamic therapy
IEEE Transactions on Biomedical Engineering, 2017Co-Authors: Jean-baptiste Tylcz, Thierry Bastogne, Alexia Bourguignon, Céline Frochot, Muriel Barberi-heyobAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. This illumination causes after a sequence of photoreactions, the production of reactive oxygen species responsible for the death of the tumor cells but also the degradation of the Photosensitizing Agent, which then loose the fluorescence properties. The phenomenon is commonly known as photobleaching process and can be considered as a therapy efficiency indicator. Methods: This paper presents the design and validation of a real time controller able to track a preset photobleaching trajectory by modulating the light impulses width during the treatment sessions. Results:This innovative solution was validated by in vivo experiments that have shown a significantly improvement of reproducibility of the inter-individual photobleaching kinetic. Conclusion: We believe that this approach could lead to personalized photodynamic therapy modalities. Significance: This work may open new perspectives in the control and optimization of photodynamic treatments.
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Realtime Tracking of the Photobleaching Trajectory During Photodynamic Therapy
IEEE transactions on bio-medical engineering, 2016Co-Authors: Jean-baptiste Tylcz, Thierry Bastogne, Alexia Bourguignon, Céline Frochot, Muriel Barberi-heyobAbstract:Objective: Photodynamic therapy (PDT) is an alternative treatment for cancer, which involves the administration of a Photosensitizing Agent that is activated by light at a specific wavelength. This illumination causes after a sequence of photoreactions, the production of reactive oxygen species responsible for the death of the tumor cells but also the degradation of the Photosensitizing Agent, which then loose the fluorescence properties. The phenomenon is commonly known as the photobleaching process and can be considered as a therapy efficiency indicator. Methods: This paper presents the design and validation of a real-time controller able to track a preset photobleaching trajectory by modulating the light impulses width during the treatment sessions. Results: This innovative solution was validated by in vivo experiments that have shown a significantly improvement of reproducibility of the interindividual photobleaching kinetic. Conclusion: We believe that this approach could lead to personalized PDT modalities. Significance: This work may open new perspectives in the control and optimization of photodynamic treatments.
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Global sensitivity analysis and estimation of photophysical parameters from in vivo data in photodynamic therapy
2012Co-Authors: Simona Dobre, Jean-baptiste Tylcz, Thierry Bastogne, Muriel Barberi-heyobAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. In this project, we aim at developing a model-based approach to compare the in vivo photodynamic efficiencies of different photosentizers. Unfortunately, constraints of in vivo experiments are such that it is impossible to estimate all the photophysical parameters. However in this paper, a feasibility study is performed to (i) select the most relevant model parameters and (ii) estimate their value and their confidence interval. Despite the previously mentioned difficulties, the results obtained in practice from in vivo experiments have shown promising results.
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Identifiability and sensitivity analysis of a Photodynamic Therapy model
Procedia - Social and Behavioral Sciences, 2010Co-Authors: Simona Dobre, Thierry Bastogne, Muriel Barberi-heyob, Alain RichardAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. The photo-toxic phase of this therapy can be described by a dynamic model composed of six nonlinear differential equations. The model parameters can be used to compare Photosensitizing Agents in their capability to produce cytotoxic species. The practical issue is their estimation from in vivo experimental data. In this paper, a new approach is proposed to analyze the photophysical parameters estimability through a local practical identifiability study combined with a global sensitivity analysis. Results show that only three parameters can reasonably be estimated in a given and realistic experimental framework. Input design (light signal) and model reduction are currently in progress.
Nino Russo - One of the best experts on this subject based on the ideXlab platform.
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22π-Electrons [1.1.1.1.1] pentaphyrin as a new Photosensitizing Agent for water disinfection: experimental and theoretical characterization
Theoretical Chemistry Accounts, 2016Co-Authors: Marta E. Alberto, Merlyn Thandu, Clara Comuzzi, Carlo Adamo, Nino RussoAbstract:In view of their promising Photosensitizing features, expanded porphyrins are gaining wide attention for their potential use both in photodynamic therapy of cancer and as likely photoactivated Agent for water disinfection. Herein, we report a joint experimental and theoretical investigation on the 20-(4′-carboxyphenyl)-2,13-dimethyl-3,12-diethyl-[22] pentaphyrin complex 4 . The synthesis, NMR, UV–Vis and mass characterization of the new compound together with a detailed theoretical investigation of the photophysical properties, are presented. In particular, type I and type II photoreactions have been explored by means of DFT and its TDDFT formulation characterizing the electronic absorption spectra, providing singlet–triplet energy gap, vertical ionization potential and electron affinity. Results show that title compound is able to generate the cytotoxic singlet oxygen species supporting the application of the proposed molecule as a photoactivated Agent for water disinfection.
Jean-baptiste Tylcz - One of the best experts on this subject based on the ideXlab platform.
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Realtime tracking of the photobleaching trajectory during photodynamic therapy
IEEE Transactions on Biomedical Engineering, 2017Co-Authors: Jean-baptiste Tylcz, Thierry Bastogne, Alexia Bourguignon, Céline Frochot, Muriel Barberi-heyobAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. This illumination causes after a sequence of photoreactions, the production of reactive oxygen species responsible for the death of the tumor cells but also the degradation of the Photosensitizing Agent, which then loose the fluorescence properties. The phenomenon is commonly known as photobleaching process and can be considered as a therapy efficiency indicator. Methods: This paper presents the design and validation of a real time controller able to track a preset photobleaching trajectory by modulating the light impulses width during the treatment sessions. Results:This innovative solution was validated by in vivo experiments that have shown a significantly improvement of reproducibility of the inter-individual photobleaching kinetic. Conclusion: We believe that this approach could lead to personalized photodynamic therapy modalities. Significance: This work may open new perspectives in the control and optimization of photodynamic treatments.
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Realtime Tracking of the Photobleaching Trajectory During Photodynamic Therapy
IEEE transactions on bio-medical engineering, 2016Co-Authors: Jean-baptiste Tylcz, Thierry Bastogne, Alexia Bourguignon, Céline Frochot, Muriel Barberi-heyobAbstract:Objective: Photodynamic therapy (PDT) is an alternative treatment for cancer, which involves the administration of a Photosensitizing Agent that is activated by light at a specific wavelength. This illumination causes after a sequence of photoreactions, the production of reactive oxygen species responsible for the death of the tumor cells but also the degradation of the Photosensitizing Agent, which then loose the fluorescence properties. The phenomenon is commonly known as the photobleaching process and can be considered as a therapy efficiency indicator. Methods: This paper presents the design and validation of a real-time controller able to track a preset photobleaching trajectory by modulating the light impulses width during the treatment sessions. Results: This innovative solution was validated by in vivo experiments that have shown a significantly improvement of reproducibility of the interindividual photobleaching kinetic. Conclusion: We believe that this approach could lead to personalized PDT modalities. Significance: This work may open new perspectives in the control and optimization of photodynamic treatments.
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Global sensitivity analysis and estimation of photophysical parameters from in vivo data in photodynamic therapy
2012Co-Authors: Simona Dobre, Jean-baptiste Tylcz, Thierry Bastogne, Muriel Barberi-heyobAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. In this project, we aim at developing a model-based approach to compare the in vivo photodynamic efficiencies of different photosentizers. Unfortunately, constraints of in vivo experiments are such that it is impossible to estimate all the photophysical parameters. However in this paper, a feasibility study is performed to (i) select the most relevant model parameters and (ii) estimate their value and their confidence interval. Despite the previously mentioned difficulties, the results obtained in practice from in vivo experiments have shown promising results.
David Kessel - One of the best experts on this subject based on the ideXlab platform.
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Photodynamic therapy: Promoting in vitro efficacy of photodynamic therapy by liposomal formulations of a Photosensitizing Agent.
Lasers in surgery and medicine, 2018Co-Authors: Imran Rizvi, Girgis Obaid, Shazia Bano, Tayyaba Hasan, David KesselAbstract:OBJECTIVE A relatively low level of lysosomal photodamage has been shown capable of promoting the efficacy of photodamage simultaneously or subsequently directed to mitochondrial/ER sites. The procedure has hitherto involved the use of two Photosensitizing Agents that require irradiation at two different wavelengths and different formulation techniques. This, together with different pharmacokinetic profiles of the photosensitizers, adds a layer of complexity to a protocol that we have sought to circumvent. In this study, liposomal formulations were used to direct photodamage created by benzoporphyrin derivative (BPD, Verteporfin) to lysosomes, mitochondria and the ER. This resulted in the development of an optimal targeting profile using a single Agent and a single wavelength of activating irradiation. MATERIALS/METHODS These studies were carried out in monolayer cultures of OVCAR5 tumor cells. BPD localization was modified by lipid anchoring and formulation in liposomes, and was assessed by fluorescence microscopy. Irradiation was carried out at 690 ± 10 nm with photodamage assessed also using fluorescent probes and microscopy. RESULTS BPD normally localizes in a wide variety of sub-cellular loci that include both mitochondria and the ER, but lysosomes are spared from photodamage. Using a liposomal formulation containing BPD anchored to a lipid resulted in the targeting of lysosomes. A mixture of liposomes containing "free" and "anchored" BPD was shown to significantly promote photokilling. Eliminating cholesterol from the formulation of the anchored product enhanced lysosomal photodamage; prior studies had revealed that excess cholesterol can have a cytoprotective effect when lysosomes are the PDT target. DISCUSSION The ability of a liposomal formulation to change localization patterns permits directing photodynamic therapy toward specific sub-cellular loci, thereby promoting photokilling. Incorporating chemotherapeutic Agents into such formulations could represent a logical next step in assessing the ability of directed photodamage to enhance tumor eradication. Lasers Surg. Med. 50:499-505, 2018. © 2018 Wiley Periodicals, Inc.
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Light-Activated Pharmaceuticals: Mechanisms and Detection.
Israel journal of chemistry, 2012Co-Authors: David Kessel, John J. ReinersAbstract:Photodynamic therapy relies on the interaction between light, oxygen and a Photosensitizing Agent. Its medical significance relates to the ability of certain Agents, usually based on porphyrin or phthalocyanine structures, to localize somewhat selectively in neoplastic cells and their vasculature. Subsequent irradiation, preferably at a sufficiently high wavelength to have a significant pathway through tissues, results in a photophysical reaction whereby the excited state of the Photosensitizing Agent transfers energy to molecular oxygen and results in the formation of reactive oxygen species. Analogous reactive nitrogen species are also formed. These contain both nitrogen and oxygen atoms. The net result is both direct tumor cell death and a shutdown of the tumor vasculature. Other processes may also occur that promote the anti-tumor response but these are outside the scope of this review.
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A mechanism for the proapoptotic activity of ursodeoxycholic acid: effects on Bcl-2 conformation.
Cell death and differentiation, 2004Co-Authors: M. Castelli, Jj Reiners, David KesselAbstract:Ursodeoxycholic acid (UDCA), a relatively nontoxic bile acid, enhanced the apoptotic response of tumor cells to both photosensitizers that cause photodamage to Bcl-2 and to the nonpeptidic Bcl-2/Bcl-xL antagonist HA14-1. The latter Agent binds to the surface pocket formed by the BH1, BH2 and BH3 domains of Bcl-2 and Bcl-xL. Fluorescence polarization studies indicated that affinity of HA14-1 for Bcl-2 was enhanced in the presence of UDCA. Moreover, Bcl-2 photodamage was promoted by UDCA using a Photosensitizing Agent with affinity for the endoplasmic reticulum, a site of Bcl-2 localization. Fluorescence resonance energy transfer (FRET) studies revealed that the proximity of Bcl-2 to a hydrophobic Photosensitizing Agent embedded in liposomes was enhanced by UDCA. Since photodamage will occur only if a protein is in close contact with a Photosensitizing Agent, we propose that these findings support the hypothesis that UDCA causes a conformational change in Bcl-2, promoting HA14-1 binding and enhancing affinity for certain membrane-bound photosensitizers.
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IMPAIRED ACCUMULATION OF A CATIONIC Photosensitizing Agent BY A CELL LINE EXHIBITING MULTIDRUG RESISTANCE
Photochemistry and photobiology, 1994Co-Authors: David Kessel, Kathryn W. Woodburn, Dimitris SkalkosAbstract:—Transport and accumulation of copper benzochlorin iminium salt (CDSl), a cationic Photosensitizing Agent, were examined using the P388/ADR murine leukemia, which exhibits the MDR (multidrug resistance) phe-notype, and the wild-type parent cell line, P388. The recent availability of radioactive CDSl permitted kinetic studies at drug levels in the submicromolar range. Exclusion of CDSl by P38WADR cells could be demonstrated, indicating that this Agent is a substrate for the outward transport system associated with MDR. These results have implications with regard to the efficacy of cationic photosensitizers against this common neoplastic phenotype. The CDSl was readily accumulated by P388 cells and by P388/ADR cells: when the outward transport system was inhibited. Under these conditions, CDSl was tightly bound and could not be washed out even when the outward transport system was reactivated.
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Lipoprotein-mediated distribution of N-aspartyl chlorin-E6 in the mouse.
Photochemistry and photobiology, 1992Co-Authors: David Kessel, K. Lane Whitcomb, Veronique SchulzAbstract:— The localization of many Photosensitizing Agents has been attributed to distribution of low density lipoprotein (LDL)-bound drug as a function of the relative numbers of LDL receptors in different tissues. While the chlorin derivative NPe6 is a potent Photosensitizing Agent in the mouse, it binds mainly to mouse plasma high density lipoproteins (HDL) and albumin, with only 1% bound to LDL. This pattern suggests only a minor role for the LDL-receptor pathway with regard to N-aspartyl chlorin e6 (NPe6) biodistribution. Moreover, patterns of accumulation of radioactive NPe6, LDL and HDL in murine tissues are consistent with the suggestion that distribution of NPe6 to different tissues cannot be explained on the basis of an LDL-mediated mechanism.
Thierry Bastogne - One of the best experts on this subject based on the ideXlab platform.
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Realtime tracking of the photobleaching trajectory during photodynamic therapy
IEEE Transactions on Biomedical Engineering, 2017Co-Authors: Jean-baptiste Tylcz, Thierry Bastogne, Alexia Bourguignon, Céline Frochot, Muriel Barberi-heyobAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. This illumination causes after a sequence of photoreactions, the production of reactive oxygen species responsible for the death of the tumor cells but also the degradation of the Photosensitizing Agent, which then loose the fluorescence properties. The phenomenon is commonly known as photobleaching process and can be considered as a therapy efficiency indicator. Methods: This paper presents the design and validation of a real time controller able to track a preset photobleaching trajectory by modulating the light impulses width during the treatment sessions. Results:This innovative solution was validated by in vivo experiments that have shown a significantly improvement of reproducibility of the inter-individual photobleaching kinetic. Conclusion: We believe that this approach could lead to personalized photodynamic therapy modalities. Significance: This work may open new perspectives in the control and optimization of photodynamic treatments.
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Realtime Tracking of the Photobleaching Trajectory During Photodynamic Therapy
IEEE transactions on bio-medical engineering, 2016Co-Authors: Jean-baptiste Tylcz, Thierry Bastogne, Alexia Bourguignon, Céline Frochot, Muriel Barberi-heyobAbstract:Objective: Photodynamic therapy (PDT) is an alternative treatment for cancer, which involves the administration of a Photosensitizing Agent that is activated by light at a specific wavelength. This illumination causes after a sequence of photoreactions, the production of reactive oxygen species responsible for the death of the tumor cells but also the degradation of the Photosensitizing Agent, which then loose the fluorescence properties. The phenomenon is commonly known as the photobleaching process and can be considered as a therapy efficiency indicator. Methods: This paper presents the design and validation of a real-time controller able to track a preset photobleaching trajectory by modulating the light impulses width during the treatment sessions. Results: This innovative solution was validated by in vivo experiments that have shown a significantly improvement of reproducibility of the interindividual photobleaching kinetic. Conclusion: We believe that this approach could lead to personalized PDT modalities. Significance: This work may open new perspectives in the control and optimization of photodynamic treatments.
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Global sensitivity analysis and estimation of photophysical parameters from in vivo data in photodynamic therapy
2012Co-Authors: Simona Dobre, Jean-baptiste Tylcz, Thierry Bastogne, Muriel Barberi-heyobAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. In this project, we aim at developing a model-based approach to compare the in vivo photodynamic efficiencies of different photosentizers. Unfortunately, constraints of in vivo experiments are such that it is impossible to estimate all the photophysical parameters. However in this paper, a feasibility study is performed to (i) select the most relevant model parameters and (ii) estimate their value and their confidence interval. Despite the previously mentioned difficulties, the results obtained in practice from in vivo experiments have shown promising results.
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Identifiability and sensitivity analysis of a Photodynamic Therapy model
Procedia - Social and Behavioral Sciences, 2010Co-Authors: Simona Dobre, Thierry Bastogne, Muriel Barberi-heyob, Alain RichardAbstract:Photodynamic therapy (PDT) is an alternative treatment for cancer that involves the administration of a Photosensitizing Agent, which is activated by light at a specific wavelength. The photo-toxic phase of this therapy can be described by a dynamic model composed of six nonlinear differential equations. The model parameters can be used to compare Photosensitizing Agents in their capability to produce cytotoxic species. The practical issue is their estimation from in vivo experimental data. In this paper, a new approach is proposed to analyze the photophysical parameters estimability through a local practical identifiability study combined with a global sensitivity analysis. Results show that only three parameters can reasonably be estimated in a given and realistic experimental framework. Input design (light signal) and model reduction are currently in progress.